There are 2 different kinds of DVD players that I know of.
This answer assumes you have a DVD burner on your computer and a blank DVD-R (who doesn't?)
Some players will play files in xVid format. I found this out when I had a bunch of DVD data discs that had xvid files on it. I tried playing it on a player that I was sure would NOT play those files, and it it did just fine. As long as your torrented movies are in avi xvid format, they should play on an xvid player. To burn those files to a DVD, just use imgBurn. It's very simple. (Also, you can put more movies on a single DVD R that way.)
Otgherwise, you'll need to "author" the DVD using a special program. I recommend "DVDFlick" - it's free and very reliable.